The present invention relates to constant velocity joints, and, more particularly, to a pulley type constant velocity joint which is capable of transmitting the rotational movement of an input shaft to an output shaft at the same velocity, and which is capable of adjusting the intersection angle of the input and output shafts within about 90xc2x0.
In general, since the wheels of an automobile are moved up and down while the automobile moves on the road, the angle between the wheel and a drive shaft is varied. A perspective view showing a conventional constant velocity joint is shown in FIG. 1, and a detailed perspective view showing the principal elements of the conventional constant velocity joint of FIG. 1. is shown in FIG. 2. As may be seen in these drawings, the conventional constant velocity joint includes input and output shafts 1 and 2 to be rotated by a driving force from the engine of an automobile, a Birfield joint 5 for adjusting the intersection angle of the input and output shafts 1 and 2, a Birfield joint boot 3, and a dust cover 7.
Here, the Birfield joint 5 includes an outer ring 11 to which the output shaft 2 is attached. The outer ring 11 is provided in its interior with an inner surface 12. Six guide grooves 13 are formed along the inner surface 12 of the outer ring 11 at regular intervals. The inner surface 12 is formed to have a truncated sphere shape.
An inner ring 14 connected with the input shaft 1 is inserted into the outer ring 11 and has an outer surface of a truncated sphere shape. A plurality of guide grooves 15 are formed along the outer surface of the inner ring 14 to correspond to the guide grooves 13 of the outer ring 11. Also, the center of the inner ring 14 has a hole 19 to be inserted on one end of the input shaft 1.
A plurality of balls (i.e., ball bearings) 16 are inserted into the spaces defined by the grooves 13 of the outer ring 11 and the grooves 15 of the inner ring 14. Additionally, a cage 18 having holes 17 corresponding to the number of the balls 16, or the number of the grooves 13 or 15 (e.g., six) which are regularly formed, is inserted between the outer ring 11 and the inner ring 14 to hold the balls 16 at the constant positions defined by the guide grooves 13 and 15. Each ball 16 is situated between opposite guide grooves 13 and 15 and holes 17 of the cage 18. The ball 16 is slidably rotated within the guide grooves 13 and 15.
The operation of the conventional constant velocity joint as described above will now be described. Each ball 16 is situated at a constant position within two opposite guide grooves 13 and 15 when the input shaft 1 is aligned with the output shaft 2, and the ball 16 is slidably situated at a position different from the constant position within the guide grooves 13 and 15 when the input shaft 1 is not aligned with the output shaft 2. Therefore, the balls 16 flexibly transmit power from the input shaft 1 to the output shaft 2 even though the axis of the two shafts 1 and 2 are not aligned with each other.
In such a case, the inner ring 14 and the outer ring 16 are brought into contact with one point of each ball 16, respectively. Furthermore, the rotating force of the inner ring 14 is transmitted to the balls 16 through the contact points between the inner ring 14 and the balls 16, and the rotating force transmitted to the balls 16 is transmitted to the outer ring 11 through the contact points between the outer ring 11 and the balls 16.
In the conventional constant velocity joint described above, the inner and outer rings 14 and 11 may become fatigue-fractured due to the concentration of stress on the contact points, and stress may well be excessively concentrated on the balls 16. In addition, the conventional constant velocity joint typically includes contact portions and guide grooves 11 and 15, which make fabrication of the joint difficult and the structure of the joint complicated.
Moreover, the conventional constant velocity joint can allow a maximum 46.5xc2x0 as the intersection angle of the input and output shafts at which the balls 16 may be kept stably within the guide grooves 13 and 15 and at which power can be transmitted from the input shaft 1 to the output shaft 2. Thus, the conventional constant velocity joint can only be used for an intersection angle of less than 46.5xc2x0.
An object of the present invention is to provide a pulley type constant velocity joint in which an elongate members or wires are wound around the circumferential grooves of two pulleys, thereby allowing the range of the intersection angle of input and output shafts to be maximized while transmitting the velocity of the input shaft to the output shaft.
Another object of the present invention is to provide a pulley type constant velocity joint in which the wires are wound around the circumferential grooves of the pulleys to allow the input and output shafts to maintain bilateral symmetry with each other and to transmit the axial rotation velocity of the input shaft to the output shaft to cause the structure of the joint to be relatively simple.
A further object of the present invention is to provide a pulley type constant velocity joint in which the wires are wound around the circumferential grooves of the pulleys to transmit the axial rotation velocity of the input shaft to the output shaft and reduce the failure rate of the joint.
To accomplish the above objects, the present invention provides a pulley type constant velocity joint which may include first and second shafts for transmitting and receiving power therebetween, first and second pulleys being fixedly attached to ends of the first and second shafts, respectively, and first and second wires wound around the circumferential grooves of the first and second pulleys to allow the first and second pulleys to be rotated with respect to the center of the first and second pulleys. Furthermore, first and second support frames may also be included for rotatably supporting each center of the first and second pulleys, both ends of which are rotatably connected with each other. The pulley type constant velocity joint may also include two rotating pins to rotatably connect with the first and second pulleys and the frames at the centers of the first and second pulleys, and two connecting pins for connecting the first and the second frames at their ends and for allowing the frames to rotate according to the rotation of the first and second shafts.
The present invention also relates to a pulley type constant velocity joint which may include first and second shafts for transmitting and receiving power therebetween, first and second pulleys being fixedly attached to each end of said first and second shafts and symmetrically rotating with respect to each center thereof as a first degree of freedom, and first and second wires wound around the circumferential grooves of the first and second pulleys to symmetrically rotate the first and second pulleys with respect to each of the centers. Additionally, first and second support frames may be included for rotatably supporting each center of the first and second pulleys and rotatably connecting both ends thereof as a second degree of freedom.
Further, the present invention also provides a pulley type constant velocity joint which may include first and second shafts, first and second pulleys, and first and second wires to make the first and second shafts have a first degree of freedom and transmit and receive power therebetween. In addition, first and second support frames may be included to make the first and second shafts have a second degree of freedom and transmit and receive power therebetween.